The present invention relates to impregnated adsorbents suitable for removing organic halide fission products in isotope processing nuclear reactors and other nuclear installations, and more particularly to a much improved impregnant therefor.
One of the nuclear fission products which results from irradiated nuclear fuel is iodine. Upon contact with atmospheric organic impurities, the iodine tends to form alkyl halides and particularly methyl iodide. It is known that adsorbents such as activated carbon can be impregnated with specific amine compounds which permit a complete steric fit of the alkyl halide concomitent with their retention on the adsorbent. Consequently, conventional methods for trapping radioactive methyl iodide (CH.sub.3.sup.131 I) use activated carbons impregnated with iodine salts and/or containing secondary and tertiary amines particularly consisting of morpholine, piperidine, piperazine, or triethylene diamine (U.S. Pat. No. 3,453,807) or with alkanol amines which contain an alkylene group of 2-6 carbon atoms (U.S. Pat. No. 3,539,653).
While such reaction between secondary and tertiary amines and halides is well known and even the use of these amines for impregnating carbon is known, the selection of such amines for forming fission product adsorbents primarily has been by trial and error; thus, optimum adsorbent impregnant combinations have not been found.
The present invention will set forth specific criteria which have been developed in order to properly evaluate the efficacy of impregnant candidates. Also, an amine which meets all of the specified criteria will be disclosed.